Semiconductor chips or dies typically are manufactured from a semiconductor material such as silicon, germanium, or gallium/arsenide. An integrated circuit or other active feature(s) is incorporated in the die adjacent one surface, often referred to as the “active surface,” of the die. The active surface typically also includes input and output terminals to facilitate electrical connection of the die with another microelectronic component.
Since semiconductor dies can be degraded by exposure to moisture and other chemical attack, most dies are encapsulated in a package that protects the dies from the surrounding environment. The packages typically include leads or other connection points that allow the encapsulated die to be electrically coupled to another electronic component, e.g., a printed circuit board. One common package design includes a semiconductor die attached to a small circuit board, e.g., via a die attach adhesive. Some or all of the terminals of the semiconductor die then may be connected electrically to a first set of contacts of the board, e.g., by wire bonding. The connected board and die may then be encapsulated in a mold compound to complete the packaged microelectronic component assembly. A second set of contacts carried on an outer surface of the board remain exposed; these exposed contacts are electrically connected to the first contacts, allowing the features of the semiconductor die to be electrically accessed.
FIG. 1 schematically illustrates a conventional packaged microelectronic component assembly 10. This microelectronic component assembly 10 includes a semiconductor die 20 having a front surface 22, which bears an array of terminals 24, and a back surface 26. This semiconductor die 20 is mounted to a front side 42 of a circuit board 40, e.g., by attaching the back surface 26 of the die 20 to the circuit board front side 42 with a die attach paste 35.
The microelectronic component assembly 10 also includes a plurality of bond wires 50 that extend from individual terminals 24 of the die 20 to bond pads 44 arranged on the front side 42 of the board 40. Typically, these bond wires 50 are attached using wire-bonding machines that spool a length of wire through a capillary. As suggested in FIG. 1, these capillaries C feed a length of wire 50 through a narrow distal passage. Typically, a molten ball is formed at a protruding end of the wire 50 and the capillary C pushes this molten ball against one of the bond pads 44, thereby attaching the terminal end of the wire 50 to the board 40, as shown. Thereafter, the capillary C spools out a length of the wire 50, presses the wire against one of the terminals 24 on the die 20, and bonds the wire to the terminal 24, e.g., by ultrasonic or thermosonic welding.
The capillaries C commonly used in the field have precisely shaped ends to insure good bonding of the wire to the bond pads 44 of circuit boards 40 and the terminals 24 of dies 20. Most capillaries C also taper outwardly moving away from this tip. As shown in FIG. 1, the capillary C will thus have an appreciable width W that must fit between the bond wire 50 in the capillary C and the top corner of the die 20. This width W will depend, in part, on the height H of the front surface 22 of the die 20 from the front side 42 of the circuit board 40. For one common type of semiconductor die, the height H is usually on the order of 100 μm. In such circumstances, the distance D between the edge of the die 20 and the bond pad 44 is over 0.2 mm, typically 0.5 mm or more, to accommodate the width W of the capillary C without unduly risking damage to the die 20. Conventional designs such as those shown in FIG. 1 often include bond pads 44 on opposing sides of the die 20. Hence, the same space D must be provided on both sides of the die 20, adding an additional 0.4 millimeters or more, typically at least 1 millimeter, to the lateral dimension of the final diced and packaged microelectronic component.
Market pressures to reduce the size of electronic devices, e.g., mobile telephones and hand-held computing devices, place a premium on the space or “real estate” available for mounting microelectronic components on a printed circuit board or the like. Similar density pressures also impact manufacturers of computers and other larger-scale electronic devices. An extra half of a millimeter per package 10, for example, can significantly add to the dimensions of an array of packaged memory chips, for example.